GCD控制线程数量

1.GCD控制线程数量

- (void)gcd_max_queue
{
    dispatch_queue_t taskConcurrentQueue = dispatch_queue_create("com.task", DISPATCH_QUEUE_CONCURRENT);
    dispatch_queue_t serialQueue = dispatch_queue_create("com.serial", DISPATCH_QUEUE_SERIAL);
    dispatch_semaphore_t semaphore = dispatch_semaphore_create(4);
    for(NSIntegeri =0; i <10; i++) {
        dispatch_async(serialQueue, ^{        dispatch_semaphore_wait(semaphore,DISPATCH_TIME_FOREVER);
            dispatch_async(taskConcurrentQueue, ^{
                NSLog(@"开始执行任务 %@", [NSThreadcurrentThread]);
                sleep(i%4);
                NSLog(@"执行任务结束 %@", [NSThreadcurrentThread]);
                dispatch_semaphore_signal(semaphore);
            });
        });
    }
}

2.GCD控制线程数量+线程任务结束通知处理

- (void)gcd_max_queue2
{
    dispatch_group_t group = dispatch_group_create();
    dispatch_semaphore_t semaphore = dispatch_semaphore_create(10);
    dispatch_queue_t queue = dispatch_get_global_queue(0, 0);
    for(NSIntegeri =0; i <20; i++) {
        dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
        dispatch_group_async(group, queue, ^{
            NSLog(@"开始执行任务 %@", [NSThreadcurrentThread]);
            sleep(i%4);
            NSLog(@"执行任务结束 %@", [NSThreadcurrentThread]);
            dispatch_semaphore_signal(semaphore);
        });
    }

    dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
        NSLog(@"总任务结束！！！ %@", [NSThreadcurrentThread]);
    });
}